A 1920s Consolidated Edison–Johns Hopkins electrocution-safety program, led by electrical engineer William Kouwenhoven, produced the closed-chest defibrillator

According to NIST's institutional account, the electric utilities that were electrocuting their own workers funded the research that would later restart stopped hearts. "In the 1920s, Consolidated Edison of New York partnered with Johns Hopkins to investigate electricity's effects on the human body," and the work found that "small electrical shocks could interfere with the natural rhythm of the human heart (a condition called ventricular fibrillation)." The mechanism cuts both ways: a shock can throw the heart into fibrillation, and a controlled counter-shock can reverse it — the principle of defibrillation.

The figure at the center is William B. Kouwenhoven, an electrical engineer, not a physician. He led the Johns Hopkins electrocution-safety program — studying lineman injuries and electrocution autopsies to set electrical-safety standards — while separately building a device to deliver the reversing counter-shock. This is the "person" hook of the lineage: cardiac-resuscitation medicine was driven forward by an engineer working on a power-industry safety brief. NIST reports the team had built a functioning closed-chest defibrillator "by the late 1950s," its prototype weighing "90 kilograms (200 pounds)."

The lineage is continuous with the telephone/power industry's earlier shock-injury research (claim-bstj-1936-published-electric-shock-heart-paper) and runs one hop further to the accidental discovery of chest-compression CPR inside this same defibrillator program (claim-chest-compression-cpr-discovered-by-accident). That lineage's oldest known link is older than Kouwenhoven's own program, though: Ferris et al.'s 1936 BSTJ paper itself credits Prevost and Battelli's 1899 work, not Kouwenhoven's, as the first report of shock-induced recovery from fibrillation, and cites Kouwenhoven's dog-recovery counter-shock work as already published by 1936 — meaning the BSTJ program and the Hopkins program were contemporaries citing a common 1899 ancestor, not strictly sequential steps in one chain (claim-ferris-1936-priority-credited-to-prevost-battelli-1899-not-kouwenhoven).

The account rests on a Tier-2 federal-agency blog with named researchers and dates; the ventricular-fibrillation mechanism is described at a general level and clears the Tier-1–2 mechanism floor for that level of detail. Specific quantitative anchors (the device weights and years) are Tier-2 secondary and not confirmed against a primary.